sex=male/female - Some species are dioecious, meaning that an individual has only male or only female flowers. A good known example are all willows (Salix).

protected=yes/no - Some trees have Tree Preservation Orders these Trees are looked after by local groups or councils. This protection can be set because of the importance for local community, protected local species, provide protection or other.

circumference=* - for the circumference of the trunk (measured in a height of 1.3 metre above ground). If no unit is given metres are assumed.

diameter_crown=* - for the diameter of the crown of foliage of the tree.

name=* - for individual trees which have a name, usually these are either individual trees with a historical or traditional name or trees with a name given in memory of special events (> memorial tree). The usual rules for name=* apply. This tag must not be used for a description of the species.

Use of redundant tags

Many tags associated with trees may be regarded as redundant as they can be derived from other tags. This is particularly true if the species is tagged (either with species or with taxon at species level or below), but in most cases also if only the Genus is tagged. In these cases properties are potentially derivable directly from the species/genus/taxon.

However it is often useful to retain (& even add) these values (e.g. genus, leaf_type, leaf_cycle) for the following reasons:

Some genera, notably the Oaks, Quercus, have species which are deciduous and others which are evergreen. Thus the combination just with genus is not adequate.

The original mapper may not have identified the tree, but did know that it was deciduous, and identification was added later.

It makes life easier for consuming the data for applications which do not require precise botanical names. Lookups on genus/species/taxon names are not always as straightforward as one might expect. Trees may have completely different generic names in different countries, or the name may have changed but mappers are using older reference material.

leaf_type & leaf_cycle are much easier to verify at most times of year. Some tree identifications will take more time than a mapper might wish to spare, but obvious changes will be easier to spot.

Subtag denotation to indicate the significance

It can be helpful to further describe the context and significance of a tree. It can be used for some maps to enhance landmarks and to tone down or skip unremarkable trees. There are some further suggestions for this on the discussion page. denotation=* seems to be widely in use. To mark monumental trees: additional monument=yes (compare to historic=monument).

Tree rows

If you want to map a line of trees, have a look at natural=tree_row. (When along a road, this is sometimes called "avenue of trees", allé or allée.) This approach can also be combined with individually mapped trees for further details.

Tree stumps / stubs

You can mark cut down trees with natural=tree_stump for stumps to reduce the probability that trees get redrawn from outdated aerial imagery.

Rendering examples

OpenStreetMap Carto (Standard layer):

- by default

- broad-leaved

- evergreen

- palms

Renderers may use one map symbol for any kind of tree. If foliage dependent symbols (as above) shall be applied, the easiest solution is to evaluate the type=*, leaf_type=* and leaf_cycle=* tags. If these are unset, you can derive them from the genus. The genus is the value of the genus=* tag. It is also the first portion (substring before the first whitespace) of the value of the species=* tag.

History

Initially this tag was supposed to be used only for lone or significant trees (As nothing in tag name itself indicated that it was not supposed to be used for ordinary trees it was used to mark trees that were neither lone nor significant - ignoring the definition on wiki).

Currently it is commonly used to mark normal trees and other tags were introduced to mark that tree is significant.